Oil well production



May 12, 1959 R. G. PIETY 2,886,108

011. WELL PRODUCTION Filed May 2, 1956 s sheets-sheet. 1

IN V EN TOR.`

l?. GL P/ETY A T rom/E rs May 12, 1959 l R. G. PIE-:TY

OIL WELL PRODUCTION 3 Sheets--Sheetl 2 Filed May 2, 1956 i INVENTOR.

I' raap/Err BY MW ATTORNEYS May 12, 1959 G. PIETY OIL WELL PRODUCTION 3 sheets-sheet :s

Filed May 2, v195%? INVENTOR.

United States Patent O OIL WELL PRODUCTION Raymond G. Piety, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Continuation of application Serial No. 302,480, August `4, 1952. This application May 2, 1956, Serial No.

3 Claims. (Cl. 166-6) This invention pertains tothe treatment and production of oil wells. In one aspect, the invention relates to 1mproved methods for the treatment and production of wells of the oilwater type. In another of its aspects, the instant invention pertains to treatment and production of gas wells. In still another of its aspects, the invention is applicationSerial No. 302,480, led August 4, 1952, now` abandoned.

Water usually ultimately appears in the well discharge in many oil iields because the producing formation is permeated in its lower portions by water under pressure. The amountof water usually increases rapidly, especially in marginal wells Iand after a few months, the wells produce more water than oil. In wells in which oil is being produced by gas drive the reservoir pressure in the oil zone will undergo 4a continuous decline, unless gas is i-njected to replace oil and gas withdrawals. A pressure differential will develop between water and oil zones and the bottom water will gradually rise and encroach into the oil reservoir. Eventually, the water rises `in the well to such an extent that the production from the well is mostly water. ln this instance, the `water cones around the well and an abnormal percentage of water is produced.

An object of the instant invention is to provide a method of oil well completion. Another object of the present invention is to provide a process for the prevention of water or gas coning. Other objects and advantages will become apparent from the accompanying explanation and disclosure.

In accordance with one aspect of this invention, a method is provided for treating wells for restoring to availability for oil delivery, portions of the formation adjacent the well which have been water-surrounded. One method within the practice of this invention, of treating an `oil-water well to prevent the encroachment of water into `the oil during production is by plugging off `the water in the well at the oil-water interface to restrict the passage of water into the well, and withdrawing oil from the formation while concomitantly circulating oil continuously to the well below the water restriction to provide a continuous iiow of oil through the water to i divert the water away from the foot of the well as the circulated oil rises around the well.

i Another method of operation in accordance with this invention, which is particularly useful for preventing formation of a `water cone, is to plug off the `water in the well at the oil-water interface to restrict the passage of water into the well, circulate oil to the water layer below the plug at a predetermined rate based on the production rate to provide a continuous iiow of oil through the Water and `subsequently begin the continuous withdrawal of oil through the `casing above the plug.

Patented May `.l2, 1959 ICC In another embodiment this invention pertains to the prevention of gas coning. The ow of circulatedloil is reversed land a packer or plug in this instance isset `at the gas-oil interface.

Oil is withdrawn from the formation beneath the packer while a predetermined quantity of oil is concomitantly recirculated to the casing above the packer, owing down the outside` of the casing to drive the gas away from the casing thereby preventing encroachment `or incursion of gas into the oil beneath the packer.

The invention will be more readily understood with reference to the accompanying drawings. The drawings are provided for the sake of clarity. It must be realized that the objects of this invention can be obtained by the employment of various types of equipment.

In Figure l is shown in elevation a welliof the type to which this invention pertains in which oil and water exist by nature adjacent each other. The figure shows water coning which results in the production of an abnormal percentage of water. i

Figure 2 is a fragmentary elevation in cross section showing one position of the plug or packer in accordance with this invention.

Figures 3 and 4 show possible positions of the oil and water interface resulting from the process of the instant invention.

lEigures 5 and 6 are also fragmentary elevations in cross section. These figures illustrate another embodiment of the invention, i.e., that adapted to wells when pumping is necessary for production.

Figures `7 and 8 are fragmentary elevations` showing the invention to prevent gas` coning.

Referring first to Figure 2 `a borehole is first drilled deeply into the sand or other producing formation below the existing water layer. Casing 1, or blank liner, is then run to the bottom ofthe hole, cemented in place in a manner well known to the art and perforated at two levels, one level ofperforations being in the oil layer and the other layer of perforations being in the water layer. A packer or `plug 3 of any desired construction is setA at the oilswater `interface between the perforations in the casing at the oil layer and the oil layer and the Aperfora-y tions at the water layer as shown in FigurevZ. The location of the interface can be done by any of the known methods of well logging. i

In accordance with this invention, a dual completion production technique is provided. Oil is continuously re-` circulated to the formation .below the oil bearing region to establish a higher pressure at the bottom ofthe formation than at the top. lThe water is then driven down and not allowed to enter the casing along with the'oil. IOil is produced from the annular space above 4a plug a"t `the oil-water interface and part of this oil is pumped back through the tubing to recirculate and` "drive back the water.

There are various methods of carrying out the process of the invention. A preferred methodr is to begin the continuous circulation of oil through `tubing 2 before production is started, usually in such a manner -that thei tion in accordance with the practice `of this invention is,

to begin production and circulation of oil simultaneously.v In some instances when this `method of production is used coning may begin before the circulating oil reaches the oil-water interface. also applicable to wells inwhich a Water cone "has already The `teachings of this invention are;`

formed. In this case, the plug will be set at the apex of the water coneas will be noted hereinafter.

One series of tests carried out in accordance with this invention showed in a quantitative way that water coning can=be prevented by the circulation into the formation directly below the producing Well of a quantity of oil of about one-tenth of the amount of oil being produced. These tests were carried out in a Lucite plastic tank so constructed that three dimensional flow could be viewed in two dimensions. The tank was coated on the inside with material to make the Lucite water wet, and then filled with unconsolidated Water-saturated sand to a level halfway between two tube openings. A similar sand saturated with oil was added to completely ll the tank. The oil phase used was kerosene, dyed red so that it might be more readily distinguished from the water. In order to have the elect of an extended aquifer a beaker of approximately the same height and diameter as the tank was filled with water and oil to levels corresponding to those in the sand. Siphon systems were arranged to replace produced fluids in simulated radial flow from this external source. The source for oil to be injected was a graduated separatory funnel suspended above the tank. Rates of injection were varied by varying the static head of the liiuid. The model was made to produce by applying a reduced pressure to the well head. This system consisted of a tube connected to a graduated cylinder, a trap and a Vacuum pump. Although produced at rates greater than necessary to cause coning under ordinary conditions, it was found that a circulation to production ratio of l volume to l0 volumes was suicient to stabilize the oilwater phase below the producing well. In accordance with this invention, the oil will pass in a continuous stream through the water. In fact in no case will the rate of circulation of oil be great enough to form an emulsion of oil and water.

The invention thus far has been discussed in connection with pressure wells, that is, wells in which oil is produced without the use of pumps, for example, due to gas pressure within the formation. The invention disclosed herein as applied to pumping wells is illustrated in Figures and 6. In the wells shown in these figures production is achieved by pump 4, oil being drawn into the pump through valves 6. The oil is then forced up tube2, but a predetermined portion of said oil is recirculated into the well below packing 3. This recirculated portion of oil passes through by-pass return channel 5 and into tube 8 extending below the packing within the casing. The amount of oil to be circulated into the c'asing below the plug will be fixed by the size of by-pass return channel 5. Figure 6 in addition to showing a pumping Well shows the position of the plug when a water cone has already formed.

Referring now to Figures 7 and 8 which show how gas coning is prevented in accordance with this invention a packer 3 is disposed in the casing at the interface as in preventing water coning, but in this instance the gas-oil interface. Circulated oil is returned to zone in the well, above the packer, and iiows down around casing through the gas phase.

A second packer 21 is provided to prevent recirculated oil from being forced upwardly by gas pressure.

In addition, pump 22 and valves 23, 24, 25 and 26 are necessary for circulating oil against the gas pressure. In a gas driven well when pump 22 is not in use, the positions of the valves are as shown in Figure 7 with valves 23, 24 and 25 open and valve 26 closed. Oil is gasdriven into tubing 14 through valves 23 and 24 and raised to the surface through tubing 16. Gas enters valve 25 to promote flow to the surface. For convenience valves 2S and 26 are contained in a housing l2. During the operation of pump 22, valves 24 and 25 will close and valve 26 will open so that gas is forced into zone 20 and returned to the oil layer. The manner in which gas coning cuts ott production in a well is shown in Figure 8. In this instance, the operation of the pump can be increased so that further coning is prevented or so that the gas cone is lled with oil.

It is seen that my invention will afford a means for overcoming diiculties due to coning, and, therefore, will result in a much improved percentage of oil in the well discharge. Given the benefit of the present disclosure other modifications and variations will, of course, occur to those skilled in the art, for example, changes in rates of circulation of oil to below the oil-water interface which will depend upon whether coning has occurred; and if a water cone has formed, whether it is to be prevented from rising higher or whether it is to be displaced downwardly. It is evident that the drawings are merelydiagrammatical and that specific details can be varied considerably without departing from the spirit or the scope of this invention.

I claim:

l. An apparatus for use in preventing gas coning in the production of oil from an oil well where an oil layer is below a gas layer which comprises, in combination, a well, a rst packer located in said well adjacent the gas-oil interface, said well being provided with perforations both above and below said first packer, a pump having an inlet and a plurality of outlets and being located within said well above said first packer, a second packer located in said well and spaced above said first packer and said perforations to form an oil return zone therebe-l tween, a iirst conduit extending downwardly through said first packer into the oil layer, said rst conduit being connected to the inlet of said pump, a second conduit connected to one of the outlets of said pump and extend# ing to the surface, the remainder of said outlets communi-` cating with said oil return zone, a valve means in said first conduit, and a plurality of valve means connected to the remainder of said outlets and in said pump for controlling the ow of oil to the surface and to said oil return zone.

2. An apparatus according to claim 1 in which said pump comprises an elongated cylindrical chamber and a piston slidably moveable from one end to the other end of said chamber, said piston having a centrally located perforation therethrough, wherein said inlet is disposed in one end of said chamber, wherein said plurality of outlets comprises a main outlet in the other end of said chamber and a plurality of perforations in the wall of said chamber, said perforations in the wall of said cham- V ber being located nearer to said main outlet than to said inlet and establishing communicationbetween said oil return zone and said chamber, wherein said valve means in said rst conduit comprises a spring-operated normally-open valve means and wherein said plurality of valve means connected to the remainder of said outlets and in said pump comprises a spring-operated normally open valve means disposed in said perforation in said piston and spring-operated valves connected to said perforations in the wall of said chamber, part of said lastmentioned valves being normally open and the remainder being normally closed.

3. A method of preventing gas coning in the production of oil from a well bore in a formation in which oil and gas exist in layers adjacent each other with the gas layer above the oil layer, said well bore extending through said gas layer and into said oil layer, which comprises sealing said well bore at a iirst point adjacent said oil layer, sealing said well bore at a second point within. said gas layer thus forming within at least a portion of the well bore in said gas layer a zone closed from thev remainder of the well bore, providing a plurality of out. lets from said zone into the surrounding gas layer, providing a discrete channel through said zone communieating between that portion of the well bore below said' rst point and the surface of the earth, passing a quantity of oil from said oil layer into said well bore below saidl first point, withdrawing said quantity of oil from said'1 well bore below said rst point, passing a portion of said quantity of Withdrawn oil into said zone and the remainder of said quantity of withdrawn oil through said channel to the surface of the earth, and passing said portion `of oil from said Zone through said outlets into said gas layer, said portion of oil being suicient in relation to said quantity of withdrawn oil to displace gas which tends to enter said oil layer from said gas layer and pass into said well bore.

References Cited in the file of this patent UNITED STATES PATENTS Schweiger Oct. 11, 1927 Buckley Feb. 8, 1944 Rose Aug. 19, 1952 West June 12, 1956 Spearow July 17, 1956 Tausch Aug. 28, 1956 

3. A METHOD OF PREVENTING GAS CONING IN THE PRODUCTION OF OIL FROM A WELL BORE IN A FORMATION IN WHICH OIL AND GAS EXIST IN LAYERS ADJACENT EACH OTHER WITH THE GAS LAYER ABOVE THE OIL LAYER, SAID WELL BORE EXTENDING THROUGH SAID GAS LAYER AND INTO SAID OIL LAYER, WHICH COMPRISES SEALING SAID WELL BORE AT A FIRST POINT ADJACENT SAID OIL LAYER, SEALING SAID WELL BORE AT A SECOND POINT WITHIN SAID GAS LAYER THUS FORMING WITHIN AT LEAST A PORTION OF THE WELL BORE IN SAID GAS LAYER A ZONE CLOSED FROM THE REMAINDER OF THE WELL BORE, PROVIDING A PLURALITY OF OUTLETS FROM SAID ZONE INTO THE SURROUNDING GAS LAYER, PROVIDING A DISCRETE CHANNEL THROUGH SAID ZONE COMMUNICATING BETWEEN THAT PORTION OF THE WELL BORE BELOW SAID FIRST POINT AND THE SURFACE OF THE EARTH, PASSING A QUANTITY OF OIL FROM SAID OIL LAYER INTO SAID WELL BORE BELOW SAID FIRST POINT, WITHDRAWING SAID QUANTITY OF OIL FROM SAID WELL BORE BELOW SAID FIRST POINT, PASSING A PORTION OF SAID QUANTITY OF WITHDRAWN OIL INTO SAID ZONE AND THE REMAINDER OF SAID QUANTITY OF WITHDRAWN OIL THROUGH SAID CHANNEL TO THE SURFACE OF THE EARTH, AND PASSING SAID PORTION OF OIL FROM SAID ZONE THROUGH SAID OUTLETS INTO SAID GAS LAYER, SAID PORTION OF OIL BEING SUFFICIENT IN RELATION TO SAID QUANTITY OF WITHDRAWN OIL TO DISPLACE GAS WHICH TENDS TO ENTER SAID OIL LAYER FROM SAID GAS LAYER AND PASS INTO SAID WELL BORE. 